Synthetic method of nitrogen-enriched carbon coated lithium titanate composite material prepared by introduction of ionic liquid as carbon source

Abstract

The invention discloses a synthetic method of a nitrogen-enriched carbon coated lithium titanate composite material prepared by the introduction of an ionic liquid as a carbon source. The synthetic method comprises the following steps of: 1) weighing lithium salt, titanium dioxide and the carbon source in proportion, adding alcohol, carrying out ball milling dispersion, and carrying out vacuum drying to prepare a precursor; 2) sintering the prepared precursor at the temperature of 750-950 DEG C under the protection of an inert atmosphere so as to preliminarily obtain lithium titanate with a carbon material coated on the surface; and 3) adding the ionic liquid and deionized water in proportion into the preliminarily obtained carbon-coated lithium titanate, carrying out ball milling, stirring and sintering. The lithium titanate composite material has a spherical morphology of nano-primary particle composed micrometer secondary particles, and the surface of the lithium titanate composite material is uniformly coated with a layer of nitrogen-enriched carbon material. Its electronic conductivity is not only effectively raised, but surface stability of the material is also enhanced. The obtained material has excellent rate capability and cycle performance. In addition, gas expansion problem of lithium titanate cells is effectively improved. The nitrogen-enriched carbon coated lithium titanate composite material has a wide application prospect in the field of lithium ion battery.

Description

technical field [0001] The present invention relates to a preparation method of lithium titanate composite material coated with nitrogen-containing carbon as negative electrode material of lithium ion battery, in particular to the method of adopting secondary coating in the material synthesis process and introducing ionic liquid as carbon source to the surface of lithium titanate. Coating treatment is carried out. The coating layer is a nitrogen-containing carbon material, which improves the cycle performance and rate performance of the material, and effectively improves the flatulence problem of the lithium titanate system battery. It belongs to the field of electrochemical material preparation technology and new energy . Background technique [0002] With the environmental problems and energy crisis attracting people's attention day by day, it is imperative to develop clean energy. In the development of new energy, lithium-ion batteries are actively developing in the dire...

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Problems solved by technology

[0003] At present, most commercial lithium-ion batteries use carbon materials as negative electrode materials, but carbon materials themselves have some disadvantages: (1) SEI film will be formed, and its first charge and discharge efficiency is low; (2) its cut-off potential is close to that of metal lithium, Lithium dendrites will be formed when the battery is overcharged, causing a short circuit and causing safety problems; (3) It has obvious voltage hysteresis; (4) It is easy to react with the electrolyte and cause the loss of the electrolyte; the spinel lithium titanate material is used as Lithium-ion battery anode materials are increasingly valued, and it has incomparable advantages compared with commercial carbon materials: it has a higher Ti 4+ / Ti 3+ (1.55V vs Li + / Li) oxidation-reduction potential, no SEI film will be formed on the surface; it has a spinel structure, and its volume hardly changes during charge and discharge, so it has a cycle life better than that of carbon anode materials; it has a three-dimensional lithium The ion diffusion channel is conducive to the rapid deintercalation reaction of lithium ions, and has excellent high-rate charge and discharge performance; it also has an ideal charge and discharge platform, and has obvious voltage mutation characteristics at the end of charging; its preparation raw materials have a wide range of sources and are clean

[0004] However, the electronic conductivity of pure phase lithium titanate is very low, which affects the charge and discharge performance of lithium ion battery electrode materials, especially its poor fast charge and discharge performance, so it must be modified to achieve the level of use.

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